1. Field of the Invention
The present invention relates to a maskless exposure apparatus, and more particularly, to a maskless exposure apparatus in which digital micro-mirror devices (DMDs) for performing exposure to a liquid crystal display (LCD) panel are arranged in an overlapping fashion and a method of manufacturing a substrate for a display using the same.
2. Description of the Related Art
In general, a panel constituting a flat panel display (FPD) is patterned by the following process. First, a patterning material is applied to a panel and selectively exposed to light using a photomask. A portion of the patterning material, which is changed in chemical properties by the selective exposure, or the other portion thereof is selectively removed to form a pattern.
Recently, a maskless exposure apparatus without using a photomask has been widely used. The maskless exposure apparatus employs a method in which an electronic device is used to transfer a light beam to a panel using pattern information in the form of electric signals. A typical example of the electronic device is a DMD. The DMD employs a principle that a plurality of micro-mirrors cause light, which is incident at a certain angle, to be reflected at a desired angle and the other light to be reflected at different angles, thereby forming a scene using only necessary light.
FIG. 1 is a schematic view illustrating the configuration of a conventional maskless exposure apparatus.
As illustrated in FIG. 1, a light source 1 provides light for an exposure process. The light from the light source 1 is transferred to a DMD 5 via a first optical system 3. The first optical system 3 includes a light guiding member 3′ and a condensing optical member 4. The light guiding member 3′ guides the light to a desired path, and the condensing optical member 4 makes the light from the light source 1 available for exposure.
The light that has passed through the condensing optical member 4 is reflected on the DMD 5. Here, the DMD 5 receives desired pattern information according to external signals and selectively transfers only necessary light to a second optical system 7 that will be described later. That is, among the light from the light source 1, the DMD 5 transfers only necessary light to the second optical system 7 while reflecting unnecessary light at other angles.
The second optical system 7 is provided with a light guiding member 7′ and an image optical member 8, which function to guide the light from the DMD 5. The light guiding member 7′ functions to guide the light to a desired path, and the image optical member 8 irradiates a substrate 10 with the light.
FIG. 2 is a schematic view illustrating a scanning process performed by DMDs of a conventional maskless exposure apparatus.
As illustrated in the figure, a substrate 10 is disposed on a scan stage 11. The scan stage 11 can be moved by an external driving source in X- and Y-axis directions, and the substrate 10 is irradiated with light.
DMDs 5 that irradiate the substrate 10 with light are placed above the scan stage 11. Generally, the DMDs 5 are arranged in a direction perpendicular to a scanning direction, as illustrated in FIG. 2. The DMDs 5 irradiate the substrate 10 with light according to pattern information while moving in a direction designated by an arrow. For reference, the scanning is performed by not a movement of the DMDs 5 itself but a relative movement of the DMDs 5 as the scan stage 11 is moved.
The number of the DMDs 5 is not limited to that illustrated in FIG. 2, but a larger number of DMDs 5 may be arranged to perform the scanning. The DMDs 5 generally perform the scanning several times rather than once. In other words, as illustrated in FIG. 2, the DMDs 5 perform the scanning while linearly reciprocating in the Y-axis direction.
However, the conventional maskless exposure apparatus described above has the following problems.
When the DMDs 5 perform the scanning, a pattern 15 is formed on the substrate 10, as shown in FIG. 3. At this time, scan marks 17 are produced in the pattern 15 due to the arrangement fashion of the DMDs 5. That is, when the DMDs 5 perform the scanning, the scan marks 17 are produced along both lateral sides and scanning boundaries of the DMDs 5. Thus, in FIG. 2, the scan marks 17 are produced along four straight lines.
Since the scan marks 17 directly appear on a screen when the substrate 10 is used for a display, there is a problem in that inconvenience is caused to a user who watches the display. That is, the scan marks 17 become a factor that deteriorates the quality of an image.